I'm a classic Overglider. After stumbling on swimsmooth last year, I worked pretty hard on getting rid of the dead spot in my stroke and increasing my stroke rate. I had some amazing times last year in Open Water Swimming thanks to this.

This year, I'm trying to apply the CSS type workouts mentioned on the site and I used the handy time-trial calculator. Well, here's the problem: the first time i input the numbers I got a 1:47 / 100yd CSS pace. So I've been using that the last 2 months and decided to take the test again as i felt much stronger in the water and my 100yd splits had definitely decreased (~1:40 range). The test this time gave me a 1:49 / 100 yd split. Something is not right.

My times this time round were 400 = 6:49 and 200 = 3:12. Toying around with the numbers, if i would have gone SLOWER on the 200, then I would have a lower CSS, this doesn't seem right. Any ideas?

Looking at your times from this test, your 200m is much quicker than the 400m, which tells the algorithm that you are fast over a shorter distance and need to do more CSS and endurance type sessions to get better over longer distance - hence giving you a higher CSS in order to help get you in the right direction when training for endurance.

So, your 400m and 200m need to be done in a way that you are sustaining your pace for both - not sprinting faster on the 200m.

I would suggest doing the test again but maintaining the same pace for both the 400m and 200m.

I found the same thing recently - the problem is, I think, that you went out too slow on the 400 CSS test, trying to pace yourself. You need to retest it, go a little quicker from the get-go, keep the pace up til the end, and this will show you your true CSS pace.I think you just aren't used to your new pace, so you mis-judged the 400 CSS pace.